The flora and structure of farmland hedges and hedgebanks near to pheasant release pens compared with other hedges

On farms where shooting takes place, hedgerows leading from woodlands with release pens are often used by pheasants as corridors for accessing game crops. We compared shrub and ground flora structure and species composition in hedges near to and away from release sites with a wide range of release sizes, at 109 game estates in four regions in England in 2002 and 2003. There was more bare ground, fewer stable perennial plant species, more weeds and fewer tree and shrub seedlings in hedges near to release sites compared to our controls, sometimes only when the nearby release exceeded a certain threshold. Alongside hedges there were more weeds on hedgebanks near to release sites, and depending on hedge size, fewer stable perennial species or fewer tree and shrub seedling species. While the woody structure of the hedge itself was not substantially different, shrub leafiness within hedges at 10-20 cm off the ground was reduced in all except very short hedges near to releases. We argue that the differences we observed were due to the presence of pheasants in those hedges during the late summer and autumn following release and not to pen siting or game management factors. We hypothesize that where larger accumulations of pheasants occur in hedges, the changes to ground flora species composition we observed were due to increased soil fertility and soil disturbance. The effects on mature shrub leafiness and woody seedlings were probably caused by direct pecking. Our study involved many sites and some of the effects identified were subtle. Our data on release size enables us to suggest how to minimise these effects where this is considered important, for example where hedgerows are recognized as particularly valuable or vulnerable.     

Chemically and biologically activated biochars slow down urea hydrolysis and improve nitrogen use efficiency

Biochar is considered a potential technology to enhance chemical fertilizer use efficiency through intensification of the interactions between nutrients and the functional groups on biochar surfaces. However, little is known about how the application of activated biochars mixed with urea influences nitrogen(N) mineralization and crop performance in paddy fields. Here, a sawdust-derived fresh biochar (FBC)(ca. 400?C) was activated chemically with 15%hydrogen peroxide and biologically with a nutri...     

土壤生物炭的生产：三种窑模型的比较研究

Biochar has potentials for soil fertility improvement, climate change mitigation and environmental reclamation, and charred biomass can be deliberately incorporated into soil for long-term carbon stabilization and soil amendment. Many different methods have been used for biochar production ranging from laboratory to industrial scales. However, in countryside of developing countries,biomass is generally used for cooking but not charred. Biochar production techniques at farmer scale have remained poorly developed.We developed and tested biochar production kilns for farmers with a dimension of 50.8 cm × 38.1 cm(height × diameter), using three different setups for optimizing oxygen(O2) limitation and syngas circulation: airtight with no syngas circulation(Model I),semi-airtight with external syngas circulation(Model II) and semi-airtight with internal syngas circulation(Model III). A comparative assessment of these biochar production kiln models was made considering biochar pyrolysis time, fuel to biomass ratio, biochar to feedstock ratio and thermogravimetric index(TGI). Among the models, the best quality biochar(TGI = 0.15) was obtained from Model I kiln taking the longest time for pyrolysis(12.5 h) and the highest amount of fuel wood(1.22 kg kg-1biomass). Model III kiln produced comparatively good quality biochar(TGI = 0.11), but with less fuel wood requirement(0.33 kg kg-1biomass) and shorter pyrolysis time(8.5 h). We also tested Model III kiln in a three times larger size under two situations(steel kiln and pit kiln). The biochar to feedstock ratio(0.38) and quality(TGI = 0.14) increased slightly for the larger kilns. Quality of biochar was found to be mainly related to pyrolysis time. The costs for the biochar stove and pit kiln were US$ 65–77, while it was US$ 154 for the large size steel kiln. Model III kiln can potentially be used for both cooking and biochar production at farmer scale.     

代乳料对羔羊生产性能及血液生化指标的影响

早期断奶可使羔羊尽早适应固体饲料,从而加快其消化道尤其是瘤胃的发育,进一步完善消化器官和消化腺的功能,为其将来采食大量饲料,提高生产性能打下基础。此外,实行早期断奶,不仅能大大降低母羊的饲养成本,而且有助于母羊提前进行生理和体况恢复,为在母羊群中实行高效高频繁殖,从而为工厂化养羊奠定基础。该试验对羔羊代乳料的饲喂效果进行了研究。     

均匀设计法优化CO_2超临界萃取细叶杜香工艺研究

目的:确定CO2超临界萃取细叶杜番的最佳工艺条件.方法:采用均匀设计,以萃取率为考察指标,对影响CO2超临界萃取因素中的萃取压力、萃取温度和萃取时间3个主要因素进行考察.结果:CO2超临界萃取细叶杜香的最佳工艺条件:萃取压力33PM,萃取温度42℃,萃取时间2.5h,在此条件下,细叶杜香挥发油的萃取率为7.90%.结论:该工艺具有萃取率高、速度快、操作简便等优点,可用于CO2超临界萃取细叶杜香.     

土壤中黄萎菌核的含量对转基因棉花发病趋势的影响

利用土壤稀释法对转基因棉花材料12花龄期、吐絮期、收获期棉花根际土壤0～20 cm耕作层中黄萎菌核的含量和转基因材料7月31日至9月11日每隔10 d的发病情况进行了调查与分析.结果表明,转基因棉花材料12发病情况在7月31日至8月11日表现明显的高温隐症,病指下降,从8月11日至9月11日发病呈一直上升的趋势;每隔10 d转基因材料的平均病情指数分别为44.53;、42.53;、54.50;、61.17;和64.03;,整个调查发病期间呈较明显的双峰趋势.从该材料的根际土壤中分离出的黄萎病菌菌落呈黑色放射状,土壤中菌核含量在调查时期则呈先降低后上升又降低的趋势,调查的三个时期1 g土壤含微菌核量分别为118.80、202.80和105.20个/g.土壤中黄萎菌核的含量与该材料的发病情况有直接的关系,这主要与黄萎菌核的病原特性有关.     

枣核中多酚物质提取条件的初步研究

以金丝小枣枣核为原料，研究了枣核多酚的提取条件，确定了邻苯二酚为枣核多酚的标准对照。采用酒石酸铁比色法测定多酚含量，通过单因素试验、正交试验对影响枣核中多酚提取效果的各因素进行了研究。结果表明，各因素对枣核多酚提取效果的影响程度从高到低依次为料液比〉pH值〉浸提温度〉浸提时间。综合考虑提取效果与生产成本，对提取条件进行了优化，确定了适宜的提取条件为：料液比1：30，pH3，80％乙醇、浸提温度50℃、浸提时间12h，枣核中多酚的含量大约为9．770mg／g。本研究为开发和利用枣产品加工中的副产品提供了一个有效的途径。     

枯草芽孢杆菌N1729对棉花主要病原菌的抑菌作用及其蛋白特性的初步研究

N1729是从棉花根际土壤分离出的拮抗细菌,通过形态、生理生化特征以及16 SrDNA的分子序列同源性分析,鉴定N1729是枯草芽孢杆菌(Bacillus subtilis).采用平板对峙法测定结果表明该菌对棉花立枯病菌、枯萎病菌和黄萎病菌均具有较强的抑菌作用,其中对立枯病菌的抑菌带最宽,为18.3 mm(3 d后),抑制率为45.7;.该菌无细胞滤液,对以上三种病原菌具有一定的抑菌作用,其中对立枯病菌的抑菌作用最好,抑制率为33.8;.还利用N1729不同稀释浓度无细胞滤液培养棉花无菌胚,发现无细胞滤液对幼苗具有一定的促生作用,稀释10倍无细胞滤液的促生作用最大,胚轴长度20.2 mm,较对照增加23.2;.通过硫酸铵沉淀法提取N1729粗提蛋白,发现该菌粗提蛋白耐高温、对氯仿不敏感、对胰蛋白酶敏感.